• So much so, more pressing factors make Chicago for the second year in a row the country's most stressful city. Crowding, poor air quality, a high 11% unemployment rate and free-falling home values have created a cocktail of constant worry affecting many in the Windy City.
• Los Angeles, Calif., ranks second, followed by New York, Cleveland, Ohio, and Providence, R.I.
• Other cities have different reasons for stress: Pittsburgh comes in second for the least amount of sunny days, and ninth for low air quality. While for years we’ve been told to avoid certain skin cancers by staying out of the sun, new research showed a link between low vitamin D levels and increased propensity to the common cold.
• It’s also believed that vitamin D receptors in cells and tissue may help regulate the immune system. Irritants in the atmosphere can cause increased incidences of asthma, chest tightness or cough.
• But there are ways to stay sane in cities while the state of the economy stays stressful. Stephen Dinwiddie, M.D., a psychiatrist at the University of Chicago, says it's important to identify what's causing stress to be able to tackle it, and to find a good balance between work and home. He also points out that one of the good things about big cities is that they offer a variety of things that can rapidly change an individual's environment. "It's easy, for example, to go to the beach or catch a Cubs game," he says. "Although I suppose some people wouldn't consider that to relieve stress."

Click here to see the full list of America's Most Stressful Cities